Fungal Fermentation on Anaerobic Digestate for Lipid-based Biofuel Precursors

Anaerobic digestate is the waste from anaerobic digestion, which still contains nutrients and lignocellulosic materials. Using these materials in the digestate can significantly improve efficiency of anaerobic digestion and generate value-added chemicals and fuel products from the organic wastes.

A Michigan State University research team, led by Yuan Zhong, developed a process that uses biogas energy to power fungal fermentation to convert remaining carbon sources and nutrients in digestate into biofuel precursor-lipids. The process contains two operations: anaerobic digestion and digestate utilization.

The process of digestate utilization involves several steps, including alkali treatment of the digestates, enzymatic hydrolysis for mono-sugar release, overliming detoxification, and fungal fermentation for lipid accumulation. The fungal fermentation led to a final lipid concentration of 3.16 g/L on the digestate with10% dry matter.

A freshwater-free process of lipid production from anaerobic digestate was developed by integrating anaerobic digestion and fungal fermentation.